Tank valves for the purpose of refilling toilet tanks after each flush cycle are well-known. They are customarily controlled by a float mechanism which opens the valve to refill the tank when its water level is too low, and closes the valve when the tank has been refilled to a correct depth.
The classical flush control is a flush valve at the bottom of the tank which is opened to release the stored water. The float follows the water level and keeps the valve open to flow until after the tank has emptied and has been refilled. The flush valve is customarily opened by lifting it with a chain or cable connected to a flush lever or handle actuated by the user.
A problem arises with this system when water leaves the tank as the consequence of loss of water for some reason other than the intentional opening of the flush valve. Examples are loss of water through a leaking flush valve, or through a crack in the tank itself. In these situations, the tank valve opens to replace the lost water even though the water was not used in a flushing cycle.
In the case of a leaking flush valve the consequences are waste of water, and the distraction caused by hearing the valve open when no one has flushed the system.
In the case of a cracked thank, instead of merely losing one tankful of water, usually drained onto the floor, water will continue to be supplied until the situation is noticed, and this may be after considerable damage has been done, especially in multi-storage buildings. To this is added the distraction, especially noticed at night, of tank refill operation when the system was not in fact flushed.
It is an object of this invention to provide means which prevent the opening of the tank valve except as the consequence of a mechanical flush motion.